The exemplary embodiments described herein relates to optical analysis systems and methods for dry cements and, in particular, to systems and methods for analyzing the characteristics, including compositions, of a dry cement.
Set cement compositions are used in the oil and gas sector for many purposes including stabilizing wellbores and plugging wellbores. Set cements are produced from cement slurries that include water, dry cements, and optionally cement slurry additives. The operational parameters relating to the cement slurry and the characteristics of the resultant set cement are derived, at least in part, from the dry cement composition and the composition and concentration of the optional cement slurry additives.
Some types of dry cements (e.g., Portland cements) are classified and graded based on its composition. Dry cement classifications broadly characterize dry cements by the concentration of the major components (or analytes) in the dry cement. For example, the multitude of American Petroleum Institute (“API”) classifications for Portland cements relate specifically to the relative concentration of four components (CaO)3.SiO2, (CaO)2.SiO2, (CaO)3.Al2O3, and (CaO)3.Al2O3.Fe2O3, whereas classifying Sorel cements may be based on the major components of MgO, MgCl2, ZnO, ZnCl2, and water.
Cement grades also relates to the composition of the dry cement, but to the minor components like metal compound concentration, sulfate concentration (e.g., sulfate salts), minor component oxide concentrations, and the like. The concentration of these minor components can affect the mechanical properties and setting chemistry of a set cement produced therefrom, which leads to variability within classifications of dry cements. For example, silicate minerals like (CaO)3.SiO2 may be used in grading a Sorel cement.
Classifying and grading a dry cement involves a complicated, multi-step process where harsh chemicals are mixed with the dry cement and then analyzed via expensive, time-consuming methods like x-ray diffraction and gravimetric analysis. Further, these classification and grading processes use equations and make assumptions that have been shown to introduce significant error into the analysis.
When the dry cement is incorrectly classified and graded, the incorrect composition and/or concentration of cement slurry additives may be used, resulting in an inefficient or ineffective cementing operation. In relation to downhole oil and gas operations, such cementing operations can increase both costs and the instances of remedial operations to repair the set cement.